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Resultados 2531-2540 de 4,294
Excessive use of nitrogenous fertilizers: an unawareness causing serious threats to environment and human health
2017
Ahmed, Moddassir | Reuf, Miḧemed | Mukhtar, Zahid | Saeed, Nasir Ahmad
Farmers occasionally need to add nitrogen fertilizer to their farms and gardens to make available just the precise nutrients for their plants’ growth. The applications of inorganic nitrogen fertilizers to various crops have been continuously increasing since last many decades globally. Although nitrogen fertilizer contributes substantially to yield enhancement, but excessive use of this manure has posed serious threats to environment and human health. Rate of nitrogen fertilizers application has a close relationship with nitrate accumulation in surrounding environment, groundwater, as well as leafy and root vegetables. Consumption of diets having high nitrate contents has contributed to endogenous nitrosation, which could lead to thyroid condition, various kinds of human cancers, neural tube defects (during fetus development), and diabetes. In this short review, the authors have tried to create awareness among general public, farming community, health practitioners, and agricultural scientists for the risk involved with excessive use of nitrogen fertilizers to human health. Carcinogenic activity and other adverse effects of N-nitroso compounds might be prevented by consuming vitamin C and antioxidants containing fruits and vegetables.
Mostrar más [+] Menos [-]Heavy metals in five Sabellidae species (Annelida, Polychaeta): ecological implications
2017
Giangrande, Adriana | Licciano, Margherita | del Pasqua, Michela | Fanizzi, Francesco Paolo | Migoni, Danilo | Stabili, Loredana
The present work analyzed three hard-bottom and two soft-bottom species of sabellid polychaetes to determine the content of several heavy metals in their branchial crown and body. The highest concentrations of heavy metals were recorded in the hard-bottom species Branchiomma bairdi, a recent Mediterranean introduction. Differences in the metal concentrations were most notable in the high trace metal levels of the branchial crown for all the studied species. Statistical analysis showed that the Mediterranean hard-bottom species were similar each other in their heavy metal content in the body as well as in the branchial crown and appeared separated from all the other species. Arsenic and vanadium hyperaccumulation in the branchial crowns of the considered sabellid species probably acts as a deterrent for predation. The observed differences among the examined species were discussed not only at the light of habitat colonization but also in terms of the phylogeny.
Mostrar más [+] Menos [-]Release of anthracene from estuarine sediments by crab bioturbation effects
2017
Sun, Nan | Chen, Yanli | Ma, Lixin | Xu, Shuqin
To investigate bioturbation effects on anthracene (Ant) release from sediments to the overlying water, indoor microcosms were developed. Naturally contaminated estuarine sediments were exposed to the crab Helice tiensinensis over 70 days and compared with sediments with no crab. Bioturbation by crab could significantly increase the release of both particulate and dissolved Ant. The releases of particulate Ant with bioturbation treatments were 2.3–11.7 times higher than in the control treatments. However, the releases of dissolved Ant with bioturbation treatments were 1.7–3.7 times higher than in the control treatments. The ratio of particulate Ant/total Ant varied from 89 % to 98 % in the bioturbation treatments, which was significantly higher than in the control treatments. These results indicate that crab bioturbation significantly enhanced both particulate and dissolved Ant release from sediment, but the particulate Ant is the predominant process.
Mostrar más [+] Menos [-]Microbial flora analysis for the degradation of beta-cypermethrin
2017
Qi, Zhang | Wei, Zhang
In the Xinjiang region of Eurasia, sustained long-term and continuous cropping of cotton over a wide expanse of land is practiced, which requires application of high levels of pyrethroid and other classes of pesticides—resulting in high levels of pesticide residues in the soil. In this study, soil samples were collected from areas of long-term continuous cotton crops with the aim of obtaining microbial resources applicable for remediation of pyrethroid pesticide contamination suitable for the soil type and climate of that area. Soil samples were first used to culture microbial flora capable of degrading beta-cypermethrin using an enrichment culture method. Structural changes and ultimate microbial floral composition during enrichment were analyzed by high-throughput sequencing. Four strains capable of degrading beta-cypermethrin were isolated and preliminarily classified. Finally, comparative rates and speeds of degradation of beta-cypermethrin between relevant microbial flora and single strains were determined. After continuous subculture for 3 weeks, soil sample microbial flora formed a new type of microbial flora by rapid succession, which showed stable growth by utilizing beta-cypermethrin as the sole carbon source (GXzq). This microbial flora mainly consisted of Pseudomonas, Hyphomicrobium, Dokdonella, and Methyloversatilis. Analysis of the microbial flora also permitted separation of four additional strains; i.e., GXZQ4, GXZQ6, GXZQ7, and GXZQ13 that, respectively, belonged to Streptomyces, Enterobacter, Streptomyces, and Pseudomonas. Under culture conditions of 37 °C and 180 rpm, the degradation rate of beta-cypermethrin by GXzq was as high as 89.84% within 96 h, which exceeded that achieved by the single strains GXZQ4, GXZQ6, GXZQ7, and GXZQ13 and their derived microbial flora GXh.
Mostrar más [+] Menos [-]Use of phytoproductivity data in the choice of native plant species to restore a degraded coal mining site amended with a stabilized industrial organic sludge
2017
Chiochetta, Claudete G. | Toumi, Hela | Böhm, Renata F. S. | Engel, Fernanda | Poyer-Radetski, Gabriel | Rörig, Leonardo R. | Adani, Fabrizio | Radetski, Claudemir M.
Coal mining-related activities result in a degraded landscape and sites associated with large amounts of dumped waste material. The arid soil resulting from acid mine drainage affects terrestrial and aquatic ecosystems, and thus, site remediation programs must be implemented to mitigate this sequential deleterious processes. A low-cost alternative material to counterbalance the affected physico-chemical-microbiological aspects of the degraded soil is the amendment with low contaminated and stabilized industrial organic sludge. The content of nutrients P and N, together with stabilized organic matter, makes this material an excellent fertilizer and soil conditioner, fostering biota colonization and succession in the degraded site. However, choice of native plant species to restore a degraded site must be guided by some minimal criteria, such as plant survival/adaptation and plant biomass productivity. Thus, in this 3-month study under environmental conditions, phytoproductivity tests with five native plant species (Surinam cherry Eugenia uniflora L., C. myrianthum–Citharexylum myrianthum, Inga–Inga spp., Brazilian peppertree Schinus terebinthifolius, and Sour cherry Prunus cerasus) were performed to assess these criteria, and additional biochemical parameters were measured in plant tissues (i.e., protein content and peroxidase activity) exposed to different soil/sludge mixture proportions. The results show that three native plants were more adequate to restore vegetation on degraded sites: Surinam cherry, C. myrianthum, and Brazilian peppertree. Thus, this study demonstrates that phytoproductivity tests associated with biochemical endpoint measurements can help in the choice of native plant species, as well as aiding in the choice of the most appropriate soil/stabilized sludge proportion in order to optimize biomass production.
Mostrar más [+] Menos [-]Effects of sublethal Abamectin exposure on some hormonal profiles and testicular histopathology in male albino rats and the possible ameliorative role of Eruca sativa
2017
Hassan, Hanaa Fawzy | Meligi, Noha M.
The ameliorative role of Eruca sativa on some hormonal profile and testicular histopathology in male albino rats exposed to a sublethal dose of 1 mg/kg body weight (b.wt). Abamectin (Crater 3.37% EC) was evaluated. Eighteen male albino rats were divided into three groups: control group, Abamectin-treated group, and Abamectin + E. sativa-treated group. Rats of the second group were orally administrated 1 mg/kg b.wt. of Abamectin, the third group received a mixture of sublethal oral dose of Abamectin (1 mg/kg b.wt.) and E. sativa suspension (5 g/kg b.wt.) every 48 h for 28 days. At the end of the study, blood samples were collected from all groups to measure some hormonal parameters; also, rats were dissected and tissue sections from the testes were prepared and stained with hematoxylin and eosin for examination under light microscope. The results of the present study revealed a disturbance in the hormonal parameters and some testicular histopathological changes. In addition, administration of E. sativa might have a promising effect against Abamectin toxicity-induced disorders of thyroid hormones and impaired testicular functions, which were correlated with histopathological changes in the testes of male rats.
Mostrar más [+] Menos [-]Effect of acute exposure to PFOA on mouse liver cells in vivo and in vitro
2017
Wu, Xinmou | Liang, Minqing | Yang, Zhao | Su, Min | Yang, Bin
Increasingly, epidemiological evidences indicate chemosynthetic perfluorooctanoic acid (PFOA), an environmental pollutant, induces potential adverse effect on human health after long-term exposure. However, less study has been performed for assessment of acute effect of PFOA exposure on metabolic homeostasis. In experimental designs, PFOA-exposed liver cells in vivo and in vitro were used to discuss underlying mechanism related to PFOA-induced metabolic dysfunction. In serological tests, PFOA-exposed mice showed increased treads of liver functional enzymes in alanine transaminase (ALT), aspartate transaminase (AST), and total bilirubin (T-BIL), trypsinase, low density lipoprotein-cholesterol (LDL-C), and insulin, while blood glucose, high density lipoprotein-cholesterol (HDL-C), and glucagon levels were reduced. In histocytological observations, PFOA-exposed liver showed visible cytoplasmic vesicles, and intact pancreatic islets were observed in PFOA-exposed pancreas. Additionally, increased insulin-positive cells and reduced glucagon-positive cells were detected in PFOA-exposed islets. As shown in immunoassays, PFOA-exposed liver resulted in elevations of cluster of differentiation 36 (CD36)-labeled cells and CD36 protein. In mouse liver cell study, PFOA-exposed cells showed increased cell apoptotic count, and increased phosphorylated levels of Bcl-2 and Bad in the cells. Furthermore, PFOA-exposed liver cells exhibited elevations of CD36-labeled cells and CD36 protein. Taken together, the present data demonstrate that acute exposure to PFOA-impaired liver function is associated with inducting CD36 expression and apoptosis, as well as disrupting key hormones in the pancreas.
Mostrar más [+] Menos [-]Removal of Anabaena spiroides by potassium permanganate pre-oxidation: effect on photosynthetic capacity and molecular weight distribution
2017
Qiao, Junlian | Zhang, Xiaodong | Lv, Liping
Bench scale tests were conducted to investigate the effect of potassium permanganate pre-oxidation on the photosynthetic activity and molecular weight distribution of Anabaena spiroides. Different concentrations of potassium permanganate were added into the suspension of Anabaena spiroides, one of the dominant algae in water bloom, and after pre-oxidation of permanganate for 1 h, the results show that the removal rate significantly increases by 33.99~36.35% compared to direct coagulation. Then, the algal characteristics, including photosynthetic ability, the changes in extracellular organic matter three-dimensional fluorescence, and the distribution of molecular weight were conducted and the results show that along with increasing concentration of potassium permanganate, the photosynthetic ability of algae decreases, more extracellular organic matter is secreted, and large molecular weight matter (humic-like and fulvic-like substances) are generated. Therefore, this study demonstrates that potassium permanganate could be used in addressing the algae-rich water.
Mostrar más [+] Menos [-]Identifying nitrate sources and transformations in Taizi River Basin, Northeast China
2017
Li, Yanli | Li, Yanfen | Zhao, Tongqian | Sun, Wei | Yang, Zirui
The nitrate (NO₃ ⁻) pollution of aquatic systems in Northeast China is a severe problem. To identify NO₃ ⁻ sources and transformations in different zones with different land uses in the Taizi River Basin, ion-exchange methods were utilized to determine the concentrations and isotopic compositions (δ¹⁵N and δ¹⁸O) of NO₃ ⁻ and chloride (Cl⁻). Results showed that Cl⁻ concentrations ranged from 2.7 to 73.4 mg/L. Cl⁻ concentrations were the highest in zone 8 and the lowest in zone 1. NO₃ ⁻ concentrations ranged from 0.3 to 27.4 mg/L and were the highest in zone 1 and the lowest in zone 8. During the sampling period, δ¹⁵N–NO₃ ⁻ values varied from 3.8 to 37.2‰, and δ¹⁸O–NO₃ ⁻ values ranged from −0.5 to 10.4‰. δ¹⁵N–NO₃ ⁻ values were the highest in zone 9 and the lowest in zone 1. The differences in physicochemical parameters and NO₃ ⁻ isotopes may be affected by land use and biogeochemical nitrogen processes in different zones. The combined analysis of dual isotopes (δ¹⁵N–NO₃ ⁻ and δ¹⁸O–NO₃ ⁻) and NO₃ ⁻/Cl⁻ versus Cl⁻ showed that different sources contributed NO₃ ⁻ to different zones during the sampling period. Soil N, manure, and sewage were the main NO₃ ⁻ sources in the Taizi River Basin. In zones 1 to 6, the δ¹⁵N–NO₃ ⁻ values of almost all samples were more than 10‰, NO₃ ⁻/Cl⁻ values were high, and Cl⁻ molar concentration was low during the sampling period. These findings suggested that the volatilization and nitrification of soil NH₄ ⁺ might be related to NO₃ ⁻ sources in zones 1 to 6. A 1:1 to 2:1 linear relationship between δ¹⁵N–NO₃ ⁻ and δ¹⁸O–NO₃ ⁻ combined with the significantly negative relationship between ln (NO₃ ⁻) and δ¹⁸O–NO₃ ⁻ indicated that denitrification affected NO₃ ⁻ distribution in zones 8 to 9 during the sampling period. These results can provide useful information to control NO₃ ⁻ concentrations in different zones in Taizi River Basin.
Mostrar más [+] Menos [-]Use of major ions to evaluate the hydrogeochemistry of groundwater influenced by reclamation and seawater intrusion, West Nile Delta, Egypt
2017
Salem, Zenhom El-Said | Osman, Osman M.
The aim of this research is to evaluate the groundwater geochemistry in western Nile Delta area as an example of an aquifer influenced by reclamation and seawater intrusion. To conduct this study, 63 groundwater samples and one surface water sample from El Nubaria Canal were collected. To estimate the origin of dissolved ions and the geochemical processes influencing this groundwater, integration between land use change, pedological, hydrogeological, hydrogeochemical, and statistical approaches was considered. Results suggest that the groundwater flow regime changed from northeast and southwest directions around El Nubaria canal before 1966 to northern and northeastern directions due to newly constructed channel network. Soil salinity and mineral contents, seepage from irrigation canal, and seawater intrusion are the main factors controlling the groundwater chemistry. Statistically, the groundwater samples were classified into eight groups, one to four for the deep groundwater and five to eight for the shallow groundwater. The deep groundwater is characterized by two groups of chemicals (SO₄–HCO₃–Mg–Ca–K and Cl–Na), while the shallow groundwater groups of chemicals are Na–Cl–SO₄ and K–HCO₃–Ca–Mg. Both shallow groundwater and deep groundwater are mostly saturated with respect to carbonate minerals and undersaturated with respect to chloride minerals. Sulfate minerals are above the saturation limit in the shallow groundwater, but in the deep samples, these minerals are under the saturation limit. Ion exchange, carbonate production, mineral precipitation, and seawater intrusion are the geochemical processes governing the groundwater chemistry in the study area.
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